Four-way reversing valve with differential area operator

ABSTRACT

The four-way reversing valve is utilized in refrigerating systems for heat pump applications to interchange the heating and cooling effects of the evaporator and condenser. The three-way pilot valve controls application of high or low system pressure to the end of the chamber adjacent the large piston. The different areas of the two pistons result in movement of the slide valve to the left (both modifications) when high pressure is applied and to the right when low pressure is applied.

United States Patent [191 Thornbery July 15, 1975 FOUR-WAY REVERSINGVALVE WITH DIFFERENTIAL AREA OPERATOR 3,448,959 6/1969 McHale et al.137/62529 X [75] Inventor: James M. Thornbery, Milwaukee, PrimaryExaminer-Arnold Rosenthal Wis. Attorney. Agenl, r FirmMichael, Best &Friedrich [73] Assignee; Controls Company of America,

S hll P k, Illv C 57 ABSTRACT [22] Filed; Mar. 14.1974

I The four-way reversing valve is utilized in refrigerating [2!] App!0384 systems for heat pump applications to interchange the heating andcooling effects of the evaporator and conl52] US. Cl. 137/6252);l37/625.43; 251/3l denser. The three-way pilot valve controlsapplication [5 1] Int. Cl. H F16k 31/363 of high or low system pressureto the end of the cham- [58] Field of Search ]37/625,29 599,1, 62543;ber adjacent the large piston. The different areas of [/3| the twopistons result in movement of the slide valve to the left (bothmodifications) when high pressure is [56] R fe Cit d applied and to theright when low pressure is applied.

UNITED STATES PATENTS 2,920,653 1/1960 Wolff 137/5991 x 4 Clams 4 Drawmgfigures M a8 Z a; z

a do -e2 06 l \JZ Q 22 FOUR-WAY REVERSING VALVE WITH DIFFERENTIAL AREAOPERATOR BACKGROUND OF THE INVENTION Reversing valves for heat pumpsystems are old with the most successful design being that shown in US.Pat. No. 2,976,7OI. That design relies upon a controlled leakage and canbe disabled by dirt. The design requires careful manufacture.

SUMMARY OF THE INVENTION The object of this invention is to provide afour-way valve which is reliable in operation. competitive in cost. hastolerance to system dirt. and can be manufactured easily with reducedtolerance requirements.

DESCRIPTION OF THE DRAWINGS FIG. 4 is a section on line 44 of FIG. 3(but can be considered a similar section in FIG. I).

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the system shown in FIG. Icompressor It) delivers hot refrigerant through conduit 12 to the slidevalve chamber 14 in the reversing valve body 16. With the slide valve 18in the position shown, the hot gas is delivered to outlet 20 and conduit22 leading to the condenser 24. Flow from the condenser 24 may beregulated by any suitable valve 26 to the evaporator 28 and flow fromthe evaporator goes through conduit 30 to port 32 below the slide valve18 with the slide valve directing the flow to outlet 34 for return tothe compressor 10 through conduit 36. Under these conditions thecondenser 24 is hot and the evaporator 28 is cold. When the flow isreversed, as explained more fully hereafter, the functions of theevaporator and condenser are reversed with the result that the formerlycold evaporator becomes hot and thus is suitable for heating the spacerather than cooling the space.

The reversing valve I6 has a central chamber 14 in which the slide valve18 is mounted. The operation of the slide valve is controlled by the twopistons 38, which are of unequal size and interconnected for movement asa unit. Pressure in chamber 42 between the piston 40 and the cylinderhead is supplied through conduit 44 from either the high pressure or lowpressure in accordance with the position of the three-way valve 46. Inthe position shown, high pressure is supplied from conduit 12 throughconduit 48, the three way valve 46, and conduit 44. Thus high pressureacts on both sides of piston 40 in the position shown in FIG. 1 with nonet force tending to move piston 40. When three-way valve 46 isactuated, low pressure is supplied to chamber 42 from conduit 36 throughconduit 52, the three-way valve 46 and conduit 44. This results in a netforce across piston 40 urging it to the right.

The left end of the valve body 16 is provided with a reduced diametercylinder 54 with chamber 56 between piston 38 and cylinder head 58. Thepressure in chamber 56 is always at low pressure conditions, beingconnected to conduit 36 through conduit 60. The two pistons areinterconnected by the rod 62 which has an oblate portion 64 straddlingslide valve 18 and connecting the rod to the valve so the piston motionwill be transferred to the valve. An oblate spring 66 underlies rodportion 64 with the spring being in the general shape of an M as seen inFIG. I. The ends of the spring bear against the ledges 68 at either endof the slide valve and the two humps of the spring bear against theunderside of the rod 64 so the slide valve 18 is held against the flatsurface 70 through which the ports 32, 34 and 20 are bored. It should benoted that the size of the cavity 72 in the slide valve and theprojection of ledges 68 are important to achieve proper timing of thevalve to prevent the system pressure being equalized during movement ofthe valve. Should that occur, the actuating forces on the pistonassembly would be neutralized and the valve would hang up.

In the position shown in FIG. I, there is equal pressure on each side ofpiston 40 as noted before. There is a pressure differential across thesmall piston 38. however. with high side pressure in chamber I4 and lowside pressure in chaamber 56. Therefore. the small piston has a forceacting on it moving it left and the pis ton assembly is held in theposition shown. If the threeway valve 46 is actuated to provide lowpressure to the chamber 42, there is now high to low pressure actingacross piston 40 just as there is across the small piston 38. Since thelarge piston has approximately twice the area of the small piston, thenet effect is a pressure derived force actuating interconnected pistonsand the slide valve I8 to the right so that flow to the condenser 24 andevaporator 28 is reversed resulting in a reversal of function so theevaporator 28, which was cold. now becomes hot and can be used forheating a space rather than cooling the space.

Both piston heads are provided with bosses or pads 37, 41 (small andlarge pistons, respectively) which engage the cylinder heads to act asstops limiting movement of the piston assembly.

The modification of FIG. 3 is not as desirable as that of FIG. I becauseit is more expensive to manufacture, but it illustrates the fact thatthere are variations possible in the construction. In this arrangementthe small diameter piston I38 and the large diameter piston 140 areinterconnected by spindle with the chamber 94 at low system pressuresupplied by conduit 96. The larger diameter cylinder 92 is mounted onthe right end of the main body 16 with ring 93 interconnecting the two.Flange 91 of the spindle 90 engages the ring 93 as illustrated in FIG. 3to limit the movement of the piston assembly to the left.

Low pressure is provided to chamber 94 through conduit 96 at all timesand can be communicated to chamber 142 between piston I40 and cylinderhead 102 if the position of the three-way valve 46 is reversed from thatillustrated. As illustrated, high side pressure is communicated throughconduit I48, the three-way valve 46, and conduit 144 to chamber 142.This, then, has a high side pressure acting in chamber 142 as well as inslide valve chamber 114. The low pressure in chamber 94 is of no effectand, therefore, the net force acting on the piston assembly is to theleft to the position shown.

The piston assembly is connected to the slide valve friction materialpad 100 which prevents deflection of the rod under the force of spring166 which acts between rod 162 and the slide valve 18 in the same manneras in FIG. 1.

If the three-way valve is now actuated, low pressure will be supplied tochamber 142. This results in a net effect of the high pressure inchamber 114 acting against low pressure in chamber 142 and, therefore,the valve assembly will move to the right to the limit determined byengagement of the boss [41 with the cylinder head 102.

The pressure differential required to initiate movement is about l psiwhich is readily attainable in an operating refrigerant system. Theforce which must be overcome is the static friction load.

I claim:

l. A reversing valve comprising,

a body including a valve chamber, a high pressure inlet to the chamber,a low pressure outlet from the chamber, and a pair of ports adjacent theoutlet,

a slide valve in the chamber movable between two positions in which itserves to connect either of said ports to said outlet while the otherport communicates with the chamber,

said body including a large diameter cylinder and a small diametercylinder,

a piston in each cylinder, the pistons being interconnected and beingconnected to the slide valve,

means supplying a constant pressure to the space between the pistons.

one side of the smaller piston being exposed to the chamber pressure andthe other side of the smaller piston being exposed to low pressure sothere is always a pressure differential acting across the smallerpiston,

means supplying high or low pressure to the space between the largerpiston and the head of the larger cylinder to cause the pistons andslide valve to move between said positions by reason of the pressuredifferential acting across the small piston area in one position and byreason of the pressure differential across the difference in pistonareas in the other position.

2. A valve according to claim 1 in which the valve chamber is betweenthe pistons.

3. A valve according to claim 1 in which both pistons are located at oneend of the valve chamber and the space between the pistons is at lowpressure.

4. The combination with a refrigeration system of the heat pump type inwhich the compressor delivers hot high pressure refrigerant to areversing valve which directs flow to one of two coils to be condensedtherein and then metered into the other of the coils from which therefrigerant flows through the reversing valve at low pressure for returnto the compressor, of an improved reversing valve, comprising,

a body including a valve chamber,

an inlet to the chamber connected to the compressor outlet whereby highsystem pressure obtains in the chamber,

an outlet from the chamber connected to the compressor suction line,

a pair of ports in the chamber, each being connected to one of thecoils,

a slide valve in the chamber movable between two positions in whicheither of the two ports comm unicates with said outlet while the otherport communicates with the chamber to direct high pressure flowto theassociated coil,

said body including two cylinders of unequal size,

a piston in each cylinder, the pistons being interconnected andconnected to the slide valve,

the space between the pistons being at a system pressure,

one side of the smaller piston being exposed to high system pressure inthe valve chamber,

and means for connecting the space between the larger piston and itsassociated cylinder head to either high or low system pressure toactuate the pistons and slide valve.

@3 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,894 561 Dated July 15, 1.975

Inventor(s) James M. Thornbery It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 4, delete claim 4.

On the Cover Sheet, after the Abstract,"'4 Claims" should read H 3Claims Signed and Scaled this sixth D y of January 1976 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner of Parentsand Trademarks

1. A reversing valve comprising, a body including a valve chamber, ahigh pressure inlet to the chamber, a low pressure outlet from thechamber, and a pair of ports adjacent the outlet, a slide valve in thechamber movable between two positions in which it serves to connecteither of said ports to said outlet while the other port communicateswith the chamber, said body including a large diameter cylinder and asmall diameter cylinder, a piston in each cylinder, the pistons beinginterconnected and being connected to the slide valve, means supplying aconstant pressure to the space between the pistons, one side of thesmaller piston being exposed to the chamber pressure and the other sideof the smaller piston being exposed to low pressure so there is always apressure differential acting across the smaller piston, means supplyinghigh or low pressure to the space between the larger piston and the headof the larger cylinder to cause the pistons and slide valve to movebetween said positions by reason of the pressure differential actingacross the small piston area in one position and by reason of thepressure differential across the difference in piston areas in the otherposition.
 2. A valve according to claim 1 in which the valve chamber isbetween the pistons.
 3. A valve according to claim 1 in which bothpistons are located at one end of the valve chamber and the spacebetween the pistons is at low pressure.
 4. The combination with arefrigeration system of the heat pump type in which the compressordelivers hot high pressure refrigerant to a reversing valve whichdirects flow to one of two coils to be condensed therein and thenmetered into the other of the coils from which the refrigerant flowsthrough the reversing valve at low pressure for return to thecompressor, of an improved reversing valve, comprising, a body includinga valve chamber, an inlet to the chamber connected to the compressoroutlet whereby high system pressure obtains in the chamber, an outletfrom the chamber connected to the compressor suction line, a pair ofports in the chamber, each being connected to one of the coils, a slidevalve in the chamber movable between two positions in which either ofthe two ports communicates with said outlet while the other portcommunicates with the chamber to direct high pressure flow to theassociated coil, said body including two cylinders of unequal size, apiston in each cylinder, the pistons being interconnected and connectedto the slide valve, the space between the pistons being at a systempressure, one side of the smaller piston being exposed to high systempressure in the valve chamber, and means for connecting the spacebetween the larger piston and its associated cylinder head to eitherhigh or low system pressure to actuate the pistons and slide valve.